Heart disease is a leading cause of death for men and women in the United States. Consequently, there are numerous medications, medical procedures, and medical devices for diagnosing and treating heart disease.
One type of medical procedure aimed at diagnosing heart disease is angiography. The procedure requires injecting a contrast agent into the blood stream and then taking x-ray images to determine if there is a blockage within the blood vessel.
A problem with an angiography is that the procedure can only determine if a blockage exists, but not whether the blockage is actually affecting the blood flow within the blood vessel. As a result, many patients elect to have unnecessary procedures to treat the blockage without confirming the severity of the blockage.
Another procedure for assessing heart disease is fractional flow reserve (FFR). FFR is a technique used in coronary catheterization to measure the pressure difference and thus blood flow across a partially blocked or constricted artery. Using a guidewire system, measurements are taken on both sides of a blockage within a blood vessel to determine if there is a pressure gradient or reduced blood flow due to the blockage. If there is no drop in pressure (or a nominal drop), then there may be no need for further medical intervention because the blockage is not significantly impeding the flow of blood. Conversely, if there is a significant drop across the blockage, then the blockage may need to be removed or treated because the blood flow is impaired by the blockage.
Generally, the FFR procedure is performed by inserting a guidewire system into the femoral or radial artery of the patient. The guidewire is maneuvered into position within a partially blocked blood vessel, and a sensor at the distal end of the guidewire is used to measure pressure, temperature, and/or blood flow to determine the severity of the blockage. The sensor is connected to a display device such as a monitor of a computer screen to display the patient's readings during the procedure.
Swept source catheters are also useful for assessing heart disease. For example, with OCT catheters, a section of a patient's vessel is scanned to accumulate linear or two dimensional image data which are used to build up a volumetric image of the blood vessel. One specific application involves the scanning of arteries, such as coronary arteries. The OCT catheter is inserted into an artery segment of interest typically using a guidewire system. The OCT catheter is then rotated and drawn back through the artery to produce a helical scan of the inner vessel wall. In a similar technology, a swept source catheter is used to determine the spectral response and thus the chemical constituents of the vessels walls, but typically not volumetric vessel images.